The present invention relates to xcfx80 complex compounds of transition metals which possess only one xcfx80 ligand (half-sandwich structure) and which have a donor-acceptor bond, the donor group or the acceptor group being bonded to the transition metal. The coordinate bond existing between the donor atom and the acceptor atom produces a (partial) positive charge in the donor group and a (partial) negative charge in the acceptor group: 
The invention further relates to a process for the preparation of such xcfx80 complex compounds of transition metals and to their use as catalysts in processes for the homopolymerization or copolymerization of monomers.
Metallocenes are known as xcfx80 complex compounds of transition metals and their use as catalysts in the polymerization of olefins is also known (EP-A 129 368 and the literature cited therein). It is also known from EP-A""368 that metallocenes, in combination with alkylaluminium/water as cocatalysts, are effective systems for the polymerization of ethylene. Thus, for example, methylaluminoxane=MAO is formed from ca. 1 mole of trimethylaluminium and 1 mole of water; other stoichiometric proportions have also already been used successfully (WO 94/20 506). The cyclopentadienyl skeletons of such metallocenes were covalently linked together by a bridge. EP-A 704 461 may be mentioned as an example of the numerous patents and patent applications in this field; the linking group mentioned in said patent is a (substituted) methylene group or ethylene group, a silylene group, a substituted silylene group, a substituted germylene group or a substituted phosphine group. EP-A""461 also designates the bridged metallocenes as polymerization catalysts. xcfx80 complex compounds suitable as polymerization catalysts are also already known which have only one xcfx80 ligand. Examples which may be mentioned are: EP 416 815, U.S. Pat. Nos. 5,453,410, 5,470,993, WO 91/04257, WO 96/13529 and U.S. Pat. No. 5,453,475. In the half-sandwich structures described therein, bonds to a central transition metal are produced on the one hand by a cyclopentadienyl anion and on the other hand by a heteroatom, these two being covalently bonded together via a bridging group. As a result, such catalysts have a forced, strained geometric structure (CGC=Constrained Geometry Catalysts).
Catalysts of the last-mentioned type are outside the framework of the present invention.
Despite the numerous patents and patent applications in this field, there is still a desire for improved catalysts which are distinguished by special properties and high activity, so that the amount of catalyst remaining in the polymer can be kept small.
It has now been found that particularly advantageous catalysts can be prepared from xcfx80 complex compounds of transition metals which have only one xcfx80 ligand and which contain a donor-acceptor bond, there being a coordinate or so-called dative bond between the donor atom and the acceptor atom, which bond is at least formally superimposed by an ionic bond, the donor group or the acceptor group being bonded to the central metal. The xcfx80 complex compounds according to the invention embrace at least two partial structures, depending on whether the donor atom D or the acceptor atom A is joined to the only xcfx80 ligand.
Accordingly, the invention relates to xcfx80 complex compounds of transition metals of the formula 
in which
xcfx80 is a charged or electrically neutral xcfx80 system which can be fused to one or two unsaturated or saturated five-membered or six-membered rings, and whose H atoms, in the fused or non-fused form, can be partially or completely replaced with identical or different radicals from the group comprising unbranched or branched C1-C20-(cyclo)alkyl, C1-C20-halogeno(cyclo)alkyl, C2--C20-(cyclo)alkenyl, C1-C20-(cyclo)alkoxy, C7-C15-aralkyl and C6-C12-aryl, or replaced in one or two instances with D or A,
D is a donor atom which, in the case of partial structure (Ia), is a substituent or part of the xcfx80 system or is bonded to the xcfx80 system via a spacer and, in the case of partial structure (Ib), is bonded to the transition metal,
A is an acceptor atom which, in the case of partial structure (Ia), is bonded to the transition metal and, in the case of partial structure (Ib), is a substituent or part of the xcfx80 system or is bonded to the xcfx80 system via a spacer,
the bonding of D or A to the transition metal taking place either directly or via a spacer, D and A being linked via a coordinate bond in such a way that the donor atom takes on a (partial) positive charge and the acceptor atom a (partial) negative charge, and it being possible for D and A in turn to carry substituents,
M is a transition metal of subgroup III to VIII of the periodic table of the elements (Mendeleeff), including the lanthanides and actinides, preferably of subgroup III to VI, including the lanthanides, and Ni,
X is one anion equivalent and
n is the number zero, one, two, three or four, depending on the charges of M and xcfx80,
D and A being specifically defined as follows:
i) in formula (Ia):
D is disubstituted N, P, As, Sb or Bi or monosubstituted or disubstituted O, S, Se or Te, bonded to xcfx80 via a spacer or directly, and
A is B, Al, Ga or In, bonded to M via a spacer or directly; or
ii) in formula (Ia), D and A together are one of the following groups bonded to xcfx80 or M via a spacer or directly: 
which represent phosphonium salts, phosphorus ylides, aminophosphonium salts and phosphinimines,
or the corresponding ammonium salts and nitrogen ylides, arsonium salts and arsenic ylides sulfonium salts and sulfur ylides, selenium salts and selenium ylides, the corresponding aminoarsonium salts and arsinimines, aminosulfonium salts and sulfimines, aminoselenium salts and selenimines, 
xe2x80x83and the corresponding sulfimine structures; or
iii) in formula (Ib):
D is disubstituted N, P, As, Sb or Bi or monosubstituted or disubstituted O, S, Se or Te, bonded to M via a spacer or directly, and
A is disubstituted Al, Ga or In, bonded to xcfx80 via a spacer or directly, or disubstituted B, bonded to xcfx80 via a spacer,
R1, R2, R3 or R4 and the expression xe2x80x9csubstitutedxe2x80x9d independently of one another are C1-C20-(cyclo)alkyl, C1-C20-halogeno(cyclo)alkyl, C2-C20-(cyclo)alkenyl, C7-C15-aralkyl, C6-C12-aryl, C1-C20-(cyclo)alkoxy, C7-C15-aralkoxy, C6-C12-arloxy, indenyl, halogen, 1-thienyl, disubstituted amino, trisubstituted silyl which can be bonded via xe2x80x94CH2xe2x80x94, or phenylacetylenyl, and xe2x80x9cSpacerxe2x80x9d is a divalent sityl, germanyl, amino, phosphino, methylene, ethylene, propylene, disilylethylene or disiloxane group which can be monosubstituted to tetrasubstituted by C1-C4-alkyl, phenyl or C4-C6-cycloalkyl, and the element P, N, As, S or Se is bonded to xcfx80 via the spacer or directly, a spacer being arranged between A and M in the case where D is part of the xcfx80 system, and xe2x80x94C(R1)xe2x95x90 also occurring as a spacer in cases i) and ii).
The following, which are listed only by way of example and are not exhaustive, are important structures covered by formulae (Ia) and (Ib): 
Preferred structures are those without spacers, with the exception of structures in which D is part of the xcfx80 system, which always contain a spacer between A and M. Structures of partial formula (Ia) are also preferred.
The xcfx80 complex compounds of transition metals according to the invention, of the above-described type (Ia or Ib) in the context of i) or iii), can be prepared, for example in a manner known to those skilled in the art, in such a way that, in the case of the partial structure of formula (Ia). either a compound of formula (II) is reacted with a compound of formula (III): 
and
Axe2x80x94MXn+1xe2x80x83xe2x80x83(III)
with the elimination of the compound YX (IV),
or a compound of formula (V) is reacted with a compound of formula (VI): 
and
MXn+1xe2x80x83xe2x80x83(VI)
with the elimination of the compound YX (IV),
or a compound of formula (VII) is reacted with a compound of formula (VIII): 
and
AYxe2x80x83xe2x80x83(VIII)
with the elimination of the compound YX (IV),
and in the case of the partial structure of formula (Ib), either a compound of formula (IX) is reacted with a compound of formula (X): 
and
Dxe2x80x94MXn+1xe2x80x83xe2x80x83(X)
with the elimination of the compound YX (IV),
or a compound of formula (XI) is reacted with a compound of formula (VI): 
and
MXn+1xe2x80x83xe2x80x83(VI)
with the elimination of the compound YX (IV),
or a compound of formula (XII) is reacted with a compound of formula (XIII): 
and
DYxe2x80x83xe2x80x83(XIII)
with the elimination of the compound YX (IV),
in the presence or absence of an aprotic solvent,
xcfx80, D, A, M, X and n being as defined above and
Y being Si(R1R2R3), Ge(R1R2R3) or Sn(R1R2R3), in which R1, R2 and R3 independently of one another are linear or branched C1-C20-(cyclo)alkyl, C1-C20-halogeno(cyclo)alkyl, C2-C20-(cyclo)alkenyl, C7-C15-aralkyl, C6-C12-aryl, vinyl, allyl or halogen, it also being possible for Y to be one cation equivalent of an alkali (alkaline earth) metal or thallium in the case where xcfx80 carries a negative charge, and it also being possible for Y to be hydrogen if X is an amide anion of the type R2Nxe2x88x92, a carbanion of the type R3Cxe2x88x92 or an alcoholate anion of the type ROxe2x88x92.
The preparation of xcfx80 complex compounds in the context of ii) of formula Ia, with the onium salts, ylides, aminoonium salts and imines contained therein, is also carried out in a manner know to those skilled in the art (A. W. Johnson, W. C. Kaska, K. A. Ostoja Starzewski, D. A. Dixon, Ylides and Imines of Phosphorus, John Wiley and Sons, Inc., New York 1993): phosphonium salts can be obtained by the quaternization of phosphines with organic halides. Dehydrohalogenation with bases in a stoichiometry of ca. 1:1 leads to phosphorus ylides. Reaction with further equivalents of base (e.g. butyllithium) gives the ylide anion with the elimination of butane: 
Further reaction with MXn, with the elimination of LiX, leads to the D/A half-sandwich complex according to the invention: 
Another equivalent of base, with dehydrohalogenation, finally yields 
The isoelectronic (Pxe2x86x92N) derivatives can be prepared analogously by starting from the aminophosphonium salts, or the starting material is a donor-substituted half-sandwich complex, e.g. 
with organic amine and carbon tetrachloride. Subsequent deprotonation gives, in the first step, 
(which is also formed from the P-substituted half-sandwich complex by reaction with organic azides or triorganosilyl azides with the subsequent elimination of N2) and, with further base, 
in the case where the nitrogen carries an H atom.
The invention further relates to the use of xcfx80 complex compounds of transition metals of the above-described type (Ia or Ib) as catalysts in processes for the homopolymerization or copolymerization of monomers from the group comprising C2-C12-xcex1-olefins, C4-C30-cycloolefins, C2-C3-alkynes, C4-C3-diolefins, C4-C3-vinyl esters and C8-C12-vinylaromatics, in the gas, solution, high-temperature solution, bulk, high-pressure or slurry phase, at xe2x88x9260xc2x0 C. to +250xc2x0 C. and 0.5 to 5000 bar, and in the presence or absence of saturated or aromatic hydrocarbons or saturated or aromatic halogenohydrocarbons, and in the presence or absence of hydrogen, the xcfx80 complex compounds being used in an amount of 10xe2x88x9212 to 10xe2x88x921 mole per mole of monomers, and it also being possible for the polymerization to be carried out in the presence of Lewis acids, Bronsted acids or Pearson acids or additionally in the presence of Lewis bases.
The donor atom D is an element of main group V or VI of the periodic table of the elements (Mendeleeff) and possesses at least one free electron pair in its particular bonding state. Examples of donor atoms are N, P, As, Sb, Bi, O, S, Se and Te, preferably N, P, As, O, S and Se and particularly preferably N, P and O. Donor atoms are in a bonding state with substituents in the case of elements of main group V and can be in such a state in the case of elements of main group VI. This is illustrated below using phosphorus and oxygen as examples of donor atoms, xe2x80x9cSubst.xe2x80x9d representing said substituents and xe2x80x9cxcfx80xe2x80x9d representing the bond to the xcfx80 system if the donor atom is bonded to the xcfx80 system. The arrow denotes the coordinate bond through a first free electron pair, and other lines denote other available electron pairs: 
Acceptor atoms A are on the one hand elements of main group III of the periodic table of the elements (Mendeleeff), such as B, Al, Ga and In, preferably B, Al or Ga, which are in a bonding state with substituents and have an electron pair gap. On the other hand, the acceptor atom A includes elements of other main groups of the periodic table of the elements which, in their bonding state, form a group, selected from nitrene, carbene and carbyne groups, acting as an acceptor.
In its bonding state, the donor atom D forms the donor group, optionally with substituents; in its bonding state, the acceptor atom A forms the acceptor group with substituents. Thus the donor group is the unit comprising the donor atom D, the substituents, if present, and the available electron pairs; by analogy, the acceptor group is the unit comprising the acceptor atom A, the substituents and the available electron pair gaps. D and A are linked by a coordinate bond, D taking on a (partial) positive charge and A a (partial) negative charge.
Examples of substituents on the donor atoms N, P, As, Sb, Bi, O, S, Se or Te and on the acceptor atoms B, Al, Ga or In are: C1-C20-(cyclo)alkyl, C1-C20-halogeno(cyclo)alkyl, C1-C20-(cyclo)alkenyl, C7-C15-aralkyl, C6-C12-aryl, C1-C20-alkoxy, C6-C12-aryloxy, C7-C15-aralkoxy, indenyl, halogen, 1-thienyl, disubstituted amino, phenylacetylenyl, trisubstituted silyl such as Si(CH3)3, or trisubstituted silyl which is bonded to D or A via xe2x80x94CH2xe2x80x94.
C1-C20-(Cyclo)alkyl is unbranched or branched and is, for example, methyl, ethyl, propyl, i-propyl, cyclopropyl, butyl, i-butyl, tert-butyl, cyclobutyl, pentyl, neopentyl, cyclopentyl, the isomeric hexyls, cyclohexyl, the isomeric heptyls, cycloheptyl, the isomeric octyls, cyclooctyl, the isomeric nonyls, decyl, undecyl, dodecyl, hexadecyl, octadecyl or eicosyl. Preferred alkyl has 1 to 6 C atoms; preferred cycloalkyl has 5 or 6 C atoms.
C1-C20-Halogeno(cyclo)alkyl is derived from said unsubstituted (cyclo)alkyls in that the H atoms are partially or completely substituted by halogen, preferably fluorine or chlorine.
C1-C20-Alkoxy substituents are derived from said C1-C20-(cyclo)alkyls in that they are bonded via an ether oxygen.
C2-C20-(Cyclo)alkenyl is linear or branched and is, for example, vinyl, allyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl or other C2-C20-(cyclo)alkenyls which differ from said (cyclo)alkyls by a terminal or internal double bond.
C7-C15-Aralkyl is, for example, tolyl, xcex1- and xcex2-phenylethyl, phenylpropyl, phenylbutyl, 1- and 2-naphthylmethyl, 1- and 2-naphthylethyl, anthrylmethyl, biphenylylmethyl or other C7-C15-aralkyls known to those skilled in the art.
C6-C12-Aryl is, for example, phenyl, 1- and 2-naphthyl or biphenylyl.
Aryloxy and aralkoxy are derived from said aryl and aralkyl radicals in that they are bonded via an ether oxygen.
The aromatic radicals contained in said substituents can be monosubstituted, disubstituted or polysubstituted by C1-C4-alkyl groups, C1-C4-alkoxy groups, C1-C4-halogenoalkyl groups, halogen, nitro, C1-C6-alkylcarboxyl, C1-C6-alkylcarbonyloxy, C1-C6-alkylcarbonyl, cyano, the sulfonic acid group or the neutralized sulfonic acid group, or several of these.
Halogen is, for example, fluorine, chlorine, bromine or iodine, preferably fluorine or chlorine.
Disubstituted amino can carry C1-C12-alkyl substituents, C6-C12-aryl substituents, C7-C15-aralkyl substituents or two different substituents of said type.
Trisubstituted silyl can carry C1-C20-alkyl substituents, C6-C12-aryl substituents, C7-C15-aralkyl substituents or a mixture of different substituents from those mentioned. Such silyl groups can also be bonded via a methylene group, an example being (CH3)3SiCH2xe2x80x94.
Preferred substituents of those mentioned are C1-C6-alkyl, C5-C6-cycloalkyl, phenyl, tolyl, C1-C6-alkoxy, C6-C12-aryloxy, vinyl, allyl, benzyl, perfluorophenyl, fluorine, chlorine, di(C1-C6-alkyl)amino and diphenylamino.
Examples of preferred donor groups are (CH3)2Nxe2x80x94, (C2H5)2Nxe2x80x94, (C3H7)2Nxe2x80x94, (C4H9)2Nxe2x80x94, (C6H5)2Nxe2x80x94, (CH3)2Pxe2x80x94, (C2H5)2Pxe2x80x94, (C3H7)2Pxe2x80x94, (i-C3H7)2Pxe2x80x94, (C4H9)2Pxe2x80x94, (t-C4H9)2Pxe2x80x94, (cyclohexyl)2Pxe2x80x94, (C6H5)2Pxe2x80x94, (CH3)(C6H5)Pxe2x80x94, Cl2Pxe2x80x94, CH3Oxe2x80x94, CH3Sxe2x80x94, C6H5Sxe2x80x94, C6H5COxe2x80x94, CH3COxe2x80x94, (CH3)3Sixe2x80x94Oxe2x80x94 and t-butyl-(CH3)2Sixe2x80x94Oxe2x80x94, in which N and P each carry one free electron pair and O and S each carry two free electron pairs, the double-bonded oxygen in some examples being bonded via a spacer group, and systems, like the pyrrolidone ring, in which the ring members other than N also act as spacers.
Examples of preferred acceptor groups are (CH3)2Bxe2x80x94, (C2H5)2Bxe2x80x94, H2Bxe2x80x94, (C6H5)2Bxe2x80x94, CH3(C6H5)Bxe2x80x94, (vinyl)2Bxe2x80x94, (benzyl)2Bxe2x80x94, Cl2Bxe2x80x94, (CH3O)2Bxe2x80x94, Cl2Alxe2x80x94, (CH3)2Alxe2x80x94, (i-C4H9)2Alxe2x80x94, (Cl)(C2H5)Alxe2x80x94, (CH3)2Gaxe2x80x94, (C3H7)2Gaxe2x80x94, ((CH3)3Sixe2x80x94CH2)2Gaxe2x80x94, (vinyl)2Gaxe2x80x94, (C6H5)2Gaxe2x80x94, (CH3)2Inxe2x80x94, ((CH3)3Sixe2x80x94CH2)2Inxe2x80x94 and (cyclopentadienyl)2Inxe2x80x94. Of said species, those in which 1 or more H atoms are replaced with fluorine are also suitable.
Other suitable donor and acceptor groups are those which contain chiral centres and in which two substituents form a ring with the D or A atom, possible examples being 
The following are examples of preferred donor-acceptor bonds: Nxe2x86x92B, Nxe2x86x92Al, Pxe2x86x92B, Pxe2x86x92Al, Oxe2x86x92B, Oxe2x86x92Al, Cxe2x95x90Oxe2x86x92B, Cxe2x95x90Oxe2x86x92Al, Pxe2x86x92C and Pxe2x86x92N.
One of D and A is bonded to the xcfx80 system, while the other is bonded to the metal M. Thus the donor atom D is bonded to the xcfx80 system in the case of partial structure (Ia), while the acceptor atom A is bonded to the xcfx80 system in the case of partial structure (Ib).
In the case where it is bonded to the xcfx80 system, D or A can be a substituent of the xcfx80 system or part of the xcfx80 system, or it can be bonded to the xcfx80 system via a spacer; the latter case also amounts to a substituent of the xcfx80 system, said substituent merely being extended by the spacer group.
The case where D or A is linked to the xcfx80 system via a spacer can be represented as follows: D-Spacer-xcfx80 or A-Spacer-xcfx80. Thus, for example, in the above examples of formulae, the moiety xe2x95x90C(R)xe2x80x94 represents such a spacer between O and xcfx80. Examples of such spacer groups are: dimethylsilyl, diethylsilyl, di-n-propylsilyl, di-1-propylsilyl, di-n-butylsilyl, di-t-butylsilyl, di-n-hexylsilyl, methylphenylsilyl, ethylmethylsilyl, diphenylsilyl, di(p-t-butylphenethyl)silyl, n-hexylmethylsilyl, cyclopentamethylenesilyl, cyclotetramethylenesilyl, cyclotrimethylenesilyl, dimethylgermanyl, diethylgermanyl, phenylamino, t-butylamino, methylamino, t-butylphosphino, ethylphosphino, phenylphosphino, methylene, dimethylmethylene (i-propylidene), diethylmethylene, ethylene, dimethylethylene, diethylethylene, dipropylethylene, propylene, dimethylpropylene, diethylpropylene, 1,1-dimethyl-3,3-dimethylpropylene, tetramethyldisiloxane, 1,1,4,4-tetramethyldisilylethylene and diphenylmethylene. Preferably, D and A are bonded without spacers to the xcfx80 system.
In the case where D or A is a substituent of the xcfx80 system, they can be located directly on the xcfx80 system, on a fused 5-membered or 6-membered ring or on another substituent of the xcfx80 system. Where there are several D or A groups, these can occupy different positions among those mentioned.
In the case where D or A is part of the xcfx80 system, heteroatomic xcfx80 systems are obtained. Accordingly, the xcfx80 systems can be carbocyclic (if D or A is a substituent of the xcfx80 system) or heterocyclic (if D or A is part of the xcfx80 system), open-chain carbon xcfx80 systems or heteroatomic xcfx80 systems. These xcfx80 systems can be electrically charged or neutral. They can also be fused with one or two unsaturated or saturated 5-membered or 6-membered rings. Examples of such fused rings are the benzene ring, the 1- or 2-naphthyl system or a cyclopentyl or cyclohexyl ring. The xcfx80 system is further characterized in that the H atoms in the entire system can be partially or completely replaced with identical or different radicals from the group comprising unbranched or branched C1-C20-(cyclo)alkyl, C1-C20-halogeno(cyclo)alkyl, C2-C20-(cyclo)alkenyl, C7-C15-aralkyl and C6-C12-aryl, or one or two H atoms can be replaced with D or A of the type described above.
xcfx80 systems according to the invention are substituted and unsubstituted ethylene, allyl, pentadienyl, benzyl, butadiene, benzene, the cyclopentadienyl anion, the cyclooctatetraene bisanion and the species obtained by replacing at least one C atom with a heteroatom. Of said species, those which are cyclic are preferred. The nature of the coordination of such xcfx80 systems (ligands) to the metal can be of the "sgr" type or of the xcfx80 type.
Examples of carboxylic xcfx80 systems are cyclopentadiene, substituted cyclopentadiene, indene, substituted indene, fluorene and substituted fluorene, which can be further substituted in the manner indicated. In the form of their anions, such skeletons containing cyclopentadiene are excellent ligands for transition metal complexes, the cyclopentadienyl carbanion compensating one positive charge of the transition metal. Specific examples of such carbanions are: cyclopentadienyl, methylcyclopentadienyl, 1,2-dimethylcyclopentadienyl, 1,3-dimethylcyclopentadienyl, 1,2-diethylcyclopentadienyl, tetramethylcyclopentadienyl, ethylcyclopentadienyl, n-butylcyclopentadienyl, n-octylcyclopentadienyl, xcex2-phenylpropylcyclopentadienyl, propylcyclopentadienyl, t-butylcyclopentadienyl, benzylcyclopentadienyl, diphenylmethylcyclopentadienyl, trimethylgermylcyclopentadienyl, trimethylstannylcyclopentadienyl, trifluoromethylcyclopentadienyl, trimethylsilylcyclopentadienyl, pentamethylcyclopentadienyl, N,N-dimethylaminocyclopentadienyl, dimethylphosphinocyclopentadienyl, methoxycyclopentadienyl, dimethylboranylcyclopentadienyl, (N,N-dimethylaminomethyl)cyclopentadienyl, indenyl, phenylindenyl, tetrahydroindenyl, fluorenyl, tetrahydro- or octahydro-fluorenyl, and fluorenyls and indenyls benzo-fused on the 6-membered ring.
Examples of heterocyclic xcfx80 systems in which D or A is part of the ring system are: 
Important heterocyclic ring systems are the systems denoted by (a), (b), (c), (d), (g), (m), (n) and (o); those denoted by (a), (b), (c) and (m) are particularly important.
In the case where one of D and A is a substituent of its corresponding ring system, the latter is 3-, 4-, 5-, 6-, 7- or 8-membered, with or without electrical charge, and can be further substituted and/or fused in the manner indicated. 5-membered and 6-membered ring systems are preferred. The negatively charged cyclopentadienyl system is particularly preferred.
Examples of heterocycles on which such xcfx80 complexes are based and which contain a donor atom from main group 5 or 6 of the periodic table of the elements (Mendeleeff) are: pyrrole, methylpyrrole, dimethylpyrrole, trimethylpyrrole, tetramethylpyrrole, t-butylpyrrole, di-t-butylpyrrole, indole, methylindole, dimethylindole, t-butylindole, di-t-butylindole, tetramethylphosphole, tetraphenylphosphole, triphenylphosphole, trimethylphosphole, phosphaindene, dibenzophosphole (phosphafluorene), dibenzopyrrole, furan, thiophene, coumarone, thionaphthene, carbazole, diphenylene oxide, diphenylene sulfide and pyridine.
An example of a heterocyclic xcfx80 system which contains an acceptor atom A as part of the system is borabenzene.
Examples of open-chain heteroatomic xcfx80 complexes are: 
R, Rxe2x80x2=H, alkyl, aryl, alkaryl, e.g. methyl, ethyl, t-butyl, phenyl or o,oxe2x80x2-di-(i-propyl)phenyl
Apart from the substituents mentioned above, the xcfx80 system can additionally be monosubstituted or disubstituted by D or A.
M is a transition metal of subgroup III to VIII of the periodic table of the elements (Mendeleeff), including the lanthanides and actinides, and preferably of subgroup III to VI, including the lanthanides, and Ni; examples which may be mentioned are: Sc, Y, La, Sm, Nd, Lu, Ti, Zr, Hf, Th, V, Nb, Ta and Cr. Of these, Ti, Zr, Hf, V, Nb, Cr and Ta are preferred and Ti, Zr and Hf are particularly preferred. Said transition metals can occur in the xcfx80 complexes according to the invention in various of their known valence states.
In the formation of the xcfx80 complex structure, one positive charge of the transition metal M is compensated by the xcfx80 complex in the case where the xcfx80 complex carries an anionic charge. In the case of electrically neutral xcfx80 systems, no positive charge of the transition metal M is compensated. In all cases, positive charges still remaining on the transition metal M are neutralized by mostly monovalent anions X. Examples of X are: hydride, chloride, methyl, ethyl, phenyl, fluoride, bromide, iodide, the n-propyl radical, the i-propyl radical, the n-butyl radical, the amyl radical, the i-amyl radical, the hexyl radical, the i-butyl radical, the heptyl radical, the octyl radical, the nonyl radical, the decyl radical, the cetyl radical, methoxy, ethoxy, propoxy, butoxy, phenoxy, dimethylamino, diethylamino, di-t-butylamino, diphenylamino, diphenylphosphino, dicyclohexylphosphino, dimethylphosphino, methylidene, ethylidene and propylidene. Two identical or different monovalent anions can also be linked together 
for example singly or doubly charged negative radicals made up of identical or different, linear or branched, saturated or unsaturated hydrocarbons, amines, phosphines, thioalcohols, alcohols or phenols. Two monoanions, such as CR3xe2x8ax96, NR2xe2x8ax96, PR2xe2x8ax96, ORxe2x8ax96, SRxe2x8ax96 etc., can be joined together by saturated or unsaturated hydrocarbon or silane bridges to form such dianions, and the number of bridging atoms can be 0, 1, 2, 3, 4, 5 or 6, 0 to 4 bridging atoms being preferred and 1 or 2 bridging atoms being particularly preferred. Apart from H atoms, these bridging atoms can also carry further hydrocarbon substituents. Possible examples of bridges between the monoanions are xe2x80x94CH2xe2x80x94, xe2x80x94CH2xe2x80x94CH2xe2x80x94, xe2x80x94(CH2)3xe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94, xe2x80x94(CHxe2x95x90CH)2xe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94, CH2xe2x80x94CHxe2x95x90CHxe2x80x94CH2xe2x80x94, xe2x80x94Si(CH3)2xe2x80x94 and xe2x80x94C(CH3)2xe2x80x94. Examples of dianions are 1,4-diphenyl-1,3-butadienediyl, 3-methyl-1,3-pentadienediyl, 1,4-dibenzyl-1,3-butadienediyl, 2,4-hexadienediyl, 1,3-pentadienediyl, 1,4-ditolyl-1,3-butadienediyl, 1,4-bis(trimethylsilyl)-1,3-butadienediyl, 1,3-butadienediyl and the ethylene glycol dianion. 1,4-Diphenyl-1,3-butadienediyl, 1,3-pentadienediyl, 1,4-dibenzyl-1,3-butadienediyl, 2,4-hexadienediyl, 3-methyl-1,3-pentadienediyl, 1,4-ditolyl-1,3-butadienediyl and 1,4-bis(trimethylsilyl)-1,3-butadienediyl are particularly preferred. Other examples of dianions are those with heteroatoms, for instance of the structure 
the bridge denoted by the curved line being as defined. Additionally, weakly coordinating or non-coordinating anions of the type mentioned below are particularly preferred for charge compensation.
Depending on the charge of M, that of the xcfx80 complex and the nature of the direct bond between A and M in the case of partial structure (Ia) or of the bond between D and M in the case of partial structure (Ib), the subscript n takes the value zero, one, two, three or four, preferably zero, one or two. Thus, depending inter alia on which of the various subgroups they belong to, the above-mentioned transition metals can have valences/charges of two to six, preferably two to four, two of which can be compensated in the case of charged xcfx80 complexes and a direct bond Axe2x80x94M or Dxe2x80x94M. Accordingly, the subscript n takes the value one in the case of La3+, for example, and the value two in the case of Zr4+, for example; n zero for Sm2+, for example.
The xcfx80 complex compounds of transition metals of formula (Ia) or (Ib) can be prepared in the case of the partial structure of formula (Ia) by reacting either a compound of formula (II) with a compound of formula (III), or a compound of formula (V) above with a compound of formula (VI) above, or a compound of formula (VII) above with a compound of formula (VIII) above, always with the elimination of the compound YX (IV), and in the case of the partial structure of formula (Ib) by reacting either a compound of formula (IX) with a compound of formula (X), or a compound of formula (XI) with a compound of formula (VI), or a compound of formula (XII) with a compound of formula (XIII), always with the elimination of the compound YX (IV). This reaction is carried out in the presence or absence of an aprotic solvent, in the temperature range from xe2x88x9278xc2x0 C. to +120xc2x0 C., preferably in the range from xe2x88x9240xc2x0 C. to +70xc2x0 C., and in a molar ratio (II):(III), (V):(VI), (VII):(VIII, (IX):(X), (XI):(VI) or (XII):(XIII) of 1:0.5 to 2, preferably 1:0.8 to 1.25 and particularly preferably 1:1. In cases where both reactants are liquid, or where at least one is liquid under the reaction conditions and is capable of dissolving or suspending the other, and/or the reaction product is also liquid, it is possible to dispense with the concomitant use of a solvent. Provided it is a liquid, the eliminated compound YX (IV) can also serve to maintain the liquid phase in the reaction according to the invention without the use of a solvent.
Y is the radical of a silane, a germane or a stannane as defined above. In the case where the xcfx80 complex carries a negative charge, Y can also be one cation equivalent of an alkali (alkaline earth) metal or thallium. Finally, Y can also be hydrogen if X is an amide anion of the type R2Nxe2x88x92, a carbanion of the type R3Cxe2x88x92 or an alcoholate anion of the type ROxe2x88x92.
Thus the eliminated compound YX can be, for example, trimethylchlorosilane, triethylchlorosilane, tri(n-butyl)chlorosilane, triphenylchlorosilane, trimethylchlorogermane, trimethylchlorostannane, TICl, LiCl, LiBr, LiF, LiI, NaCl, NaBr, KCl, KF, MgCl2, MgBr2, CaCl2, CaF2, an amine R2NH or R2NY, a hydrocarbon compound of the formula R3CH or R3CY, or an ether ROY, in which Y is Si(R1R2R3), Ge(R1R2R3) or Sn(R1R2R3). Accordingly, further examples of the compounds YX are dimethylamine, diethylamine, di(n-propyl)amine, di(i-propyl)amine, di(t-butyl)amine, t-butylamine, cyclohexylamine, aniline, methylphenylamine, diallylamine, methane, toluene, trimethylsilylamine, trimethylsilyl ether, tetramethylsilane and analogous compounds familiar to those skilled in the art.
In the reaction according to the invention, one component having a readily cleavable leaving group Y is reacted with one compound having a transition metal and at least one replaceable anion X. The readily cleavable leaving group can be located here on a xcfx80 system with an associated donor atom (II) or with an associated acceptor atom A (IX) or on a c complex with an already preformed D/A bond (V) or (XI). However, the readily cleavable leaving group can also be introduced into the process in the form of a compound with the (substituted) donor atom D (XIII) or as a compound with the (substituted) acceptor atom A (VIII). The transition metal is introduced into the reaction in a symmetrical form thereto.
Both the starting materials of the preparative process, namely (II), (V), (VII), (IX), (XI) or (XII) on the one hand and (III), (VI), (VIII), (X) or (XIII), react spontaneously when brought together, with the simultaneous formation of the donor-acceptor bond, if this has not already been preformed, or with the simultaneous complexation of the transition metal, and with the elimination of the compound YX.
For the sake of clarity, the substituents on D and A have been omitted in the formula representation of the donor-acceptor bond.
In the case of the concomitant use of solvents in the preparative process according to the invention, these are polar or non-polar aprotic solvents such as aliphatic and aromatic hydrocarbons or aliphatic and aromatic halogenohydrocarbons. In principle, other aprotic solvents, such as those known to those skilled in the art, can also be used, although those with excessively high boiling points are less preferable in terms of the ease of working-up. Typical examples are: n-hexane, cyclohexane, pentane, heptane, petroleum ether, toluene, benzene, chlorobenzene, methylene chloride, diethyl ether, tetrahydrofuran and ethylene glycol dimethyl ether.
The starting materials for the process according to the invention can be prepared by processes known in the literature or by analogous processes. Thus, for example, analogously to J. of Organometallic Chem. 29, (1971), 227, the commercially available trimethylsilylcyclopentadiene can be reacted first with butyllithium and then with trimethylsilyl chloride to give bis(trimethylsilyl)cyclopentadiene. This in turn can be reacted with boron trichloride to give trimethylsilylcyclopentadienyldichloroborane (analogously to J. of Organometallic Chem. 169, (1979), 327), which can finally be reacted with titanium tetrachloride to give dichloroborylcyclopentadienyltitanium trichloride analogously to J. of Organometallic Chem. 169, (1979), 373. This last-mentioned compound is covered by formula (XII) above. By reaction with trimethylaluminium, the two chlorine atoms bonded to the boron atom can be exchanged for methyl groups. Analogously to the descriptions of processes in J. Am. Chem. Soc. 105, (1983), 3882 and Organometallics 1, (1982), 1591, the commercially available cyclopentadienylthallium can be reacted with chlorodiphenylphosphine and further with butyllithium to give precursors of formula (VII). Another example which may be mentioned is the formation of dimethylstannyldiphenylphosphinoindene by reacting indene first with butyllithium, as already mentioned above, and then with chlorodiphenylphosphine; further reaction, first with butyllithium again and then with chlorotributyltin, gives the target compound, which, after further reaction with zirconium tetrachloride, gives diphenylphosphinoindenylzirconium trichloride as a representative of formula (VII). Such syntheses and preparative procedures are familiar to those skilled in the art who work in the field of metal-organic and element-organic chemistry, and are published in numerous literature references, only a few of which have been cited above as examples. The examples listed at the end of the general description show how heterocyclic precursors are obtainable for the xcfx80 complex compounds of transition metals according to the invention. Thus pyrrolyllithium can be prepared from pyrrole by reaction with butyllithium, for instance as described in J. Am. Chem. Soc. 104, (1982), 2031. Trimethylstannylphosphole is obtained by reacting 1-phenylphosphole with lithium and then with aluminium trichloride to give phospholyllithium, which in turn reacts further with trimethylchlorostannane to give trimethylstannylphosphole (cf. J. Chem. Soc., Chem. Comm. 1988, 770). This compound can be reacted with titanium tetrachloride to give phospholyltitanium trichloride. Analogously, known preparative processes exist for open-chain xcfx80 complex compounds made up of carbon atoms only or with incorporated heteroatoms, which can be provided with donor groups or acceptor groups analogously to the methods mentioned.
The onium salt, ylide/imine and ylide anion/imine anion structures mentioned above in connection with ii) in the context of formula (Ia) can be synthesized by processes known to those skilled in the art (cf. literature cited above).
The xcfx80 complex compounds of transition metals of formulae (Ia) and (Ib) according to the invention can be used as catalysts in polymerization processes. Such homopolymerization or copolymerization processes are carried out in the gas, solution, high-temperature solution, bulk, high-pressure or slurry phase at xe2x88x9260 to +250xc2x0 C., preferably 0 to 200xc2x0 C., and 0.5 to 5000 bar, preferably 1 to 3000 bar, in the presence or absence of saturated or aromatic hydrocarbons or saturated or aromatic halogenohydrocarbons, and in the presence or absence of hydrogen, the xcfx80 complex compounds being used in an amount of 10xe2x88x922 to 10xe2x88x921 mole per mole of monomers. Such polymerization processes can be carried out batchwise or, preferably, continuously. Likewise, the polymerization can be carried out in a semibatch process. Such processes can also be carried out in more than one reactor or more than one reaction zone. If several reaction zones are involved, it is possible to employ different polymerization conditions therein. Thus, in one reactor, it is possible to form a prepolymer which, in subsequent reactors, is particularly suitable as a heterogeneous catalyst for the actual (co)polymerization. Insoluble heterogeneous D/A catalysts in the form of the xcfx80 complex compounds according to the invention on inorganic supports are particularly suitable for the formation of such prepolymers.
The xcfx80 complex compounds according to the invention can be employed for the (co)polymerization in the isolated form as pure substances, but they can also be produced and used xe2x80x9cin situxe2x80x9d in the (co)polymerization reactor in a manner known to those skilled in the art. The xcfx80 complex compounds according to the invention can be present in both mononuclear and polynuclear form.
According to the invention, the xcfx80 complex compounds can also be used in the presence of Lewis acids, Brxc3x6nsted acids or Pearson acids or additionally in the presence of Lewis bases. Examples of such Lewis acids are boranes or alanes such as alkylaluminium compounds, aluminium halides, aluminium alcoholates, organoboron compounds, boron halides, boric acid esters or boron or aluminium compounds containing both halide and alkyl, aryl or alcoholate substituents, as well as mixtures thereof, or the triphenylmethyl cation. Aluminoxanes or mixtures of aluminium-containing Lewis acids with water are particularly preferred. According to current knowledge, all acids work as ionizing agents to form a xcfx80 complex cation which is charge-compensated by a bulky, poorly coordinating anion. Such compounds act as cocatalysts. Other cocatalysts apart from those mentioned are alkyllithium compounds, organomagnesium compounds such as Grignard compounds, or partially hydrolyzed organoboron compounds. Preferred cocatalysts are aluminoxanes. Examples of aluminoxane compounds are those of the formula 
in which
R is C1-C20-alkyl, C6-C12-aryl or benzyl and
n is a number from 2 to 50, preferably 10 to 35.
It is also possible to use a mixture of different aluminoxanes or a mixture of their precursors (alkylaluminium compounds) in combination with water (in gaseous, liquid, solid or bound form, for instance as water of crystallization). The water can also be introduced as (residual) moisture in the polymerization medium, the monomer or a support like silica gel. The boron compounds analogous to formula (XIV) are suitable as well. The bonds projecting from the square brackets of formula (XIV) carry R groups or AIR2 groups as end groups of the oligomeric aluminoxane. Such aluminoxanes are normally present as a mixture of several with different chain lengths. Detailed study has also revealed aluminoxanes of cyclic or cage-like structure. Aluminoxanes are commercially available compounds. In the special case where Rxe2x95x90CH3, they are referred to as methylaluminoxanes (MAO).
The activation with the cocatalyst or the production of the bulky non-coordinating or weakly coordinating anion can be carried out in an autoclave or in a separate reaction vessel (preformation). The activation can be effected in the presence or absence of the monomer(s) to be polymerized. The activation can be carried out in an aliphatic, aromatic or halogenated solvent or suspending agent.
The xcfx80 complex compounds or metallocene compounds and the aluminoxanes can be used either as such in homogeneous form or individually or together in heterogeneous form on supports. Said support can be of an inorganic or organic nature, such as silica gel, Al2O3, MgCl2, NaCl, B2O3, polysiloxanes, cellulose derivatives, cyclodextrins, starch derivatives and other polymers like polyethylene or polypropylene. It is possible here to apply either the xcfx80 complex compound or metallocene compound first or to apply the aluminoxane first to the support and then to add the other component. By the same token, however, it is also possible to activate the xcfx80 complex compound or metallocene compound in homogeneous or heterogeneous form with the aluminoxane and then to apply the activated metallocene compound to the support, which is optionally loaded with aluminoxane.
The supports are preferably thermally and/or chemically pretreated in order to adjust the water content or the OH group concentration to a defined value or keep it as low as possible. A chemical pretreatment can consist e.g. in the reaction of the support with alkylaluminium compound. Inorganic supports are usually heated at 100xc2x0 C. to 1000xc2x0 C. for 1 to 100 hours before use. The surface area of such inorganic supports, especially of silica (SiO2), is between 10 and 1000 m2/g, preferably between 100 and 800 m2/g. The particle diameter is between 0.1 and 500 micrometres (xcexc), preferably between 10 and 200xcexc.
The relative proportions of xcfx80 complex compounds and cocatalyst are 1 to 100,000 mole of cocatalyst per mole of xcfx80 complex compound.
According to the invention, it is also possible to use the reaction products of the above-described ionizing agents with xcfx80 complex compounds of formulae (Ia) to (Id). They can be described by formulae (XVa) to (XVd): 
Base represents a Lewis base.
Examples of poorly coordinating anions are borates and alanates, for example: 
sulfonates such as tosylate or triflate, tetrafluoroborates, hexafluorophosphates, hexafluoroantimonates, perchlorates and bulky cluster molecular anions of the carborane type, for example C2B9H12xe2x8ax96 or CB11H12xe2x8ax96. When such anions are present, metallocene compounds can also work as high-efficiency polymerization catalysts in the absence of aluminoxane. This is the case particularly when one xcfx80 ligand is an alkyl group, allyl or benzyl. It can also be advantageous, however, to use such metallocene complexes with bulky anions in combination with alkylaluminium compounds such as (CH3)3Al, (C2H5)3Al, (n-/i-propyl)3Al, (n-/t-butyl)3Al, (i-butyl)3Al or the isomeric pentyl-, hexyl- or octyl-aluminium compounds, alkyllithium compounds such as methyl-Li, benzyl-Li or butyl-Li, or the corresponding organomagnesium compounds such as Grignard compounds, or organozinc compounds. On the one hand such metal alkyls transfer alkyl groups to the central metal, and on the other hand they trap water or catalyst poisons from the reaction medium or monomer during polymerization reactions. Metal alkyls of the type described can also advantageously be used in combination with aluminoxane cocatalysts, for instance to reduce the required amount of aluminoxane. Such anions are introduced when using e.g. the following boron compounds:
triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, tri(n-butyl)ammonium tetraphenylborate, tri(t-butyl)ammonium tetraphenylborate, N,N-dimethylanilinium tetraphenylborate, N,N-diethylanilinium tetraphenylborate, N,N-dimethyl(2,4,6-trimethylanilinium) tetraphenylborate, trimethylammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate, tri(sec-butyl)ammonium tetrakis(pentafluorophenyl)borate, N,N-diethylanilinium tetrakis(pentafluorophenyl)borate, N,N-diethylanilinium tetrakis(pentafluorophenyl)borate, N,N-dimethyl(2,4,5-trimethylanilinium) tetrakis(pentafluorophenyl)borate, trimethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, triethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, tripropylammonium tetrakis(2,3,4,6-tetrafluorophenyl) borate, tri(n-butyl)ammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, dimethyl(t-butyl)ammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N-dimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate, N,N-diethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate and N,N-dimethyl(2,4,6-trimethylanilinium) tetrakis(2,3,4,6-tetrafluorophenyl)borate; dialkylammonium salts such as: di(i-propyl)ammonium tetrakis(pentafluorophenyl)borate and dicyclohexylammonium tetrakis(pentafluorophenyl)borate; trisubstituted phosphonium salts such as: triphenylphosphonium tetrakis(pentafluorophenyl)borate, tri(o-tolyl)phosphonium tetrakis(pentafluorophenyl)borate and tri(2,6-dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate; tritolylmethyl tetrakis(pentafluorophenyl)borate; triphenylmethyl tetraphenylborate (trityl tetraphenylborate); trityl tetrakis(pentafluorophenyl)borate; silver tetrafluoroborate; tris(pentafluorophenyl)borane; tris(trifluoromethyl)borane; and the corresponding organoaluminium compounds.
Further alternative possibilities are fluorinated but otherwise analogous boron and aluminium compounds having 1 to 3 fluorine substituents.
Other poorly coordinating anions can be formed from diboranyl or dialanyl compounds of the type 
Activation by means of such bulky anions is effected for example by reacting the xcfx80 complex compounds having a D/A bond with tris(pentafluorophenyl)borane, triphenylborane, triphenylaluminium, trityl tetrakis(pentafluorophenyl)borate or N,N-dialkylphenylammonium tetrakis(pentafluorophenyl)borate, as well as the corresponding alanes and alanates, or the corresponding phosphonium or sulfonium salts of borates, or alkali (alkaline earth) metal, thallium or silver salts of borates or alanates, carboranes, tosylates, triflates, perfluorocarboxylates, such as trifluoroacetate, or the corresponding acids. The xcfx80 complex compounds of transition metals used are preferably those whose anion equivalents X are alkyl, allyl, aryl or benzyl groups. Such derivatives can also be prepared xe2x80x9cin situxe2x80x9d by first reacting xcfx80 complex compounds which have other anion equivalents X, such as F, Cl, Br, OR etc., with alkylaluminium compounds, organolithium compounds, Grignard compounds or alkylzinc or alkyllead compounds. The resulting reaction products can be activated with the above-mentioned boranes, borates, alanes or alanates without prior isolation.
It is also within the framework of the present invention simultaneously to use several xcfx80 complex compounds having a D/A bond in order to produce a particular profile of material properties. Accordingly, it is also possible to use one or more xcfx80 complex compounds having a D/A bond in combination with other xcfx80 complex compounds which do not have a D/A bond.
The use according to the invention of the xcfx80 complex compounds of transition metals with a D/A bond concerns the homopolymerization or copolymerization of monomers from the group comprising C2-C12-xcex1-olefins, C4-C30-cycloolefins, C4-C8-diolefins, C2-C8-alkynes, C4-C8-vinyl esters and C8-C12-vinylaromatics.
Examples of olefins of said type are ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 4-methyl-1-pentene, 4-methyl-1-hexene and (xcex1-i-octene. Such olefins can also be substituted, for example by phenyl, substituted phenyl, halogen, an esterified carboxyl group or an acid anhydride group; this provides access to the group comprising said vinylaromatics and vinyl esters and other olefinically unsaturated compounds, for example styrene, methylstyrene, chlorostyrene, fluorostyrene, 4-vinylbiphenyl, vinylfluorene, vinylanthracene, methyl methacrylate, ethyl acrylate, vinylsilane, trimethylallylsilane, vinyl chloride, vinylidene chloride, tetrafluoroethylene, vinylcarbazole, vinylpyrrolidine, vinyl ethers and vinyl esters such as vinyl acetate or vinyl propionate. Preferred monomers are ethylene, propylene, butene, hexene, octene and methyl methacrylate.
Cyclic monomers are monocyclic or polycyclic and are covered by one of the two formulae below: 
in which the subscripts are defined as follows:
m is a number from 2 to 10, preferably 3 to 6,
n is the number 0 or 1,
o is the number 0, 1, 2 or 3 and
p is the number 0 or 1,
in formula (XVI) two adjacent CH2 groups can be replaced with the group xe2x80x94CHxe2x95x90CHxe2x80x94, and in formula (XVII) the radicals R1a to R6a and R7 to R20 independently of one another are hydrogen, fluorine, chlorine, bromine, linear or branched C1-C20-alkyl, C3-C8-cycloalkyl or C6-C16-aryl, it additionally being possible for the pair of radicals R18/R19 to be a double bond or one of the groups xe2x80x94CHR21xe2x80x94CHR22xe2x80x94CHR23, xe2x80x94CHR21xe2x80x94CHR22xe2x80x94CHR23xe2x80x94CHR24xe2x80x94 or xe2x80x94CHR21xe2x80x94CHR22xe2x80x94CHR23xe2x80x94CHR24xe2x80x94CHR25xe2x80x94, in which R21 to R25 are hydrogen or C1-C4-alkyl, and it being possible for the pair of radicals R17/R18 to be the double-bonded group xe2x95x90C(R26,R27), in which R26 and R27 are C1-C4-alkyl and R27 can also be hydrogen.
Such cyclic monomers have one or more double bonds, preferably one or two double bonds, and are known; they are used for example in the processes of EP-A 610 852, EP-A 690 078 and U.S. Pat. No. 5,567,777.
Preferred cyclic monomers of formula (XVII) are those of the formulae 
A non-exhaustive list of examples of such cyclic comonomers includes cyclobutene, cyclopentene, cyclopentadiene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, cyclododecene, bicyclo-2-heptenes, tricyclo-3-decenes, tricyclo-3-undecenes, tetracyclo-3-dodecenes, pentacyclo-4-pentadecenes, pentacyclopentadecadienes, pentacyclo-3-pentadecenes, pentacyclo-4-hexadecenes, pentacyclo-3-hexadecenes, hexacyclo-4-heptadecenes, heptacyclo-5-eicosenes, heptacyclo-4-eicosenes, heptacyclo-5-heneicosenes, octacyclo-5-docosenes, nonacyclo-5-pentacosenes, nonacyclo-6-hexacosenes, cyclopentadiene/acenaphthylene adducts, 1,4-methano-1,4,4a,9a-tetrahydrofluorenes and 1,4-methano-1,4,4a,5,10,10a-hexahydroanthracenes, e.g. bicyclo[2.2.1]hept-2-ene (norbornene), norbornadiene, 5-methylnorbornene, 6-methylnorbornene, 5,6-dimethylnorbornene, 1-methylnorbornene, 5-isobutylnorbornene, 7-methylnorbornene, tricyclo[4.3.0.12,5]-3-decene (5,6-trimethylenenorbornene), tricyclo[4.4.0.12,5]-3-undecene (5,6-tetramethylenenorbornene), 10-methyltricyclo[4.4.0.12,5]-3-undecene, 6-ethylbicyclo[2.2.1]hept-2-ene, 6-n-butylbicyclo[2.2.1]hept-2-ene, 6-isobutylbicyclo[2.2.1]hept-2-ene, 2-methyltricyclo[4.3.0.12,5]-3-decene, 5-methyltricyclo[4.3.0.12,5]-3-decene, tricyclo[4.3.0.12,5]-3-undecene, tricyclo[4.3.0.12,5]-3,7-decadiene (dicyclopentadiene), tricyclo[4.3.0.12,5]-3-decene, tetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-methyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-cyclohexyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-stearyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, the 5,10-dimethyl, 2,10-dimethyl, 8,9-dimethyl, 11,12-dimethyl, 2,7,9-trimethyl, 9-isobutyl, 11,12-dimethyl, 8-ethylidene-9-methyl, 8-chloro, 8-bromo or 8-fluoro derivative of tetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-methyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-propyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-butyltetracyclo[4.4.0.12,5.1 7,10]-3-dodecene, 8-isobutyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-hexyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-methyl-9-ethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 9-ethyl-2,7-dimethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 9-isobutyl-2,7-dimethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 9,11,12-trimethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 9-ethyl-11,12-dimethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 9-isobutyl-11,12-dimethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 5,8,9,10-tetramethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-ethylidenetetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-ethylidene-9-methyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-ethylidene-9-ethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-ethylidene-9-isopropyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-ethylidene-8-butyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-n-propylidenetetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-n-propylidene-9-methyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-n-propylidene-9-ethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-n-propylidene-9-isopropyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-n-propylidene-9-butyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-isopropylidenetetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-isopropylidene-9-methyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-isopropylidene-9-ethyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-isopropylidene-9-isopropyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-isopropylidene-9-butyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8,9-dichlorotetracyclo[4.4.0.12,5.17,10]-3-dodecene, pentacyclo[6.5.1.13,6.02,7.09,13]-4-pentadecene, pentacyclo[7.4.0.12,5.19,12.08,13]-3-pentadecene, pentacyclo[8.4.0.12,5.19,12.08,13]-3-hexadecene, 1,3-dimethylpentacyclo[6.5.1.13,6.02,7.09,13]-4-pentadecene, 1,6-dimethyl[6.5.1.13,6.02,7.09,13]-4-pentadecene, 14,15-dimethyl[6.5.1.13,6.02,7.09,13]-4-pentadecene, pentacyclo[7.4.0.12,5.19,12.08,13]-3-pentadecene, methyl-substituted pentacyclo[7.4.0.12,5.19,12.08,13]-3-pentadecene, pentacyclo[6.5.1.13,6.02,7.09,13]-4,10-pentadecadiene, 11-methylpentacyclo[8.4.0.12,5.19,12.08,13]-3-hexadecene, 11-ethyl[8.4.0.12,5.19,12.08,13]-3-hexadecene, 10,11-dimethyl[8.4.0.12,5.19,12.08,13]-3-hexadecene, pentacyclo[6.6.1.13,6.02,7.09,14]-hexadecene, 1,3-dimethylpentacyclo[6.6.1.13,6.02,7.09,14]-4-hexadecene, 15,16-dimethylpentacyclo[6.6.1.13,6.02,7.09,14]-4-hexadecene, hexacyclo[6.6.1.13.6.110,13.02,7.09,14]heptadecene, heptacyclo[8.7.0.12,9.14,7.111,17.012,16]-5-eicosene, heptacyclo[8.8.0.14,7.111,18.113,16.03,8.012,17]-5-heneicosene, 12-methylhexacyclo[6.6.1.13,6.110,13.02,7.09,14]-4-heptadecene, 12-ethylhexacyclo[6.6.1.13,6.110,13.02,7.09,14]-4-heptadecene, 12-isobutylhexacyclo[6.6.1.13,6.110,13.02,7.09,14]-4-heptadecene, 1,6,10-trirethylhexacyclo[6.6.1.13,6.110,13.02,7.09,14]-4-heptadecene, heptacyclo[8.7.0.13,6.110,17.112,15.02,7.011,16]-4-eicosene and its dimethyl-substituted derivatives, heptacyclo[8.8.0.14,7.111,18.113,16.03,8.012,17]-5-heneicosene and its trimethyl-substituted derivatives, 15-methylheptacyclo[8.8.0.14,7.111,18.113,16.03,8.012,17]-5-heneicosene, 5-phenylbicyclo[2.2.1]hept-2-ene, 5-methyl-5-phenylbicyclo[2.2.1]hept-2-ene, 5-benzylbicyclo[2.2.1]hept-2-ene, 5-tolylbicyclo[2.2.1]hept-2-ene, 2-(ethylphenyl)bicyclo[2.2.1]hept-2-ene, 5-(isopropylphenyl)bicyclo[2.2.1]hept-2-ene, 5-biphenylbicyclo[2.2.1]hept-2-ene, 5-(xcex2-naphthyl)bicyclo[2.2.1]hept-2-ene, 5-(xcex1-naphthyl)bicyclo[2.2.1]hept-2-ene, 5-(anthracenyl)bicyclo[2.2.1]hept-2-ene, 5,6-diphenylbicyclo[2.2.1]hept-2-ene, 1,4-methano-1,4,4a,9a-tetrahydrofluorene, 1,4-methano-1,4,4a,5,10,10a-hexahydroanthracene, 8-phenyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-methyl-8-phenyltetracyclo[4.4.0.12,5,17,10]-3-dodecene, 8-benzyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-tolyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-(ethylphenyl)tetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-(isopropylphenyl)tetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8,9-diphenyltetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-(biphenyl)tetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-(xcex2-naphthyl)tetracyclo[4.4.0.12,5.17,10]-3-dodecene, 8-(xcex1-naphthyl)tetracyclo[4.4.0.12,5.17,10]-3-dodecene, and 8-(anthracenyl)tetracyclo[4.4.0.12,5.17,10]-3-dodecene.
The homopolymerizations or copolymerizations to be carried out with the xcfx80 complex compounds according to the invention are performed under adiabatic or isothermal conditions. This entails high-pressure processes in autoclaves or tubular reactors, solution or high-temperature solution processes, bulk polymerization processes, slurry phase polymerization processes in stirred reactors or loop reactors, and gas phase processes, the pressures for the slurry, solution and gas phases generally not exceeding 65 bar. All these processes have been known as such for a long time and are familiar to those skilled in the art. It is an advantage of the xcfx80 complex compounds according to the invention that, by choosing the substituents, they can be prepared either as soluble xcfx80 complex compounds, optionally applied to supports, or as insoluble heterogeneous xcfx80 complex compounds.
Examples of polymers which can be prepared with the xcfx80 complex compounds according to the invention are linear high density polyethylene (HDPE), isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), syndiotactic polystyrene, i- or s-polybutene or -polyhexene, polyoctene, polybutadiene, linear low density copolymer, e.g. ethylene with C3-C20-xcex1-olefin (linear low density polyethylene, LLDPE), for example ethylene/propylene, ethylene/butylene, ethylene/hexene and ethylene/octene, and also, for instance, propylene/butylene, propylene/hexene, ethylene/styrene, propylene/styrene, 1,3-butadiene/ethylene, 1,3-butadiene/styrene, the analogous isoprene copolymers etc. Possible examples of readily obtainable terpolymers are ethylene/propylene/ethylidenenorbornene (ENB), ethylene/propylene/dicyclopentadiene, ethylene/propylene/vinylnorbornene and ethylene/propylene/7-methyloctadiene.
Through the donor-acceptor bridge, the xcfx80 complex compounds to be used according to the invention allow a definite opening of the active centre, particularly also for sterically demanding monomers, thereby ensuring not only a high activity but also a controlled selectivity, a controlled molecular weight distribution and a uniform incorporation of (co)monomers. A high uniformity of the molecular weight distribution is also a consequence of the uniform and definite site of the polymerization effected by insertion (single site catalyst). Furthermore, the xcfx80 complex compounds according to the invention make it possible to obtain products with long branched chains in the polymerization process, which have the effect of improving the rheology.
The D/A bond can stabilize the catalysts right up to high temperatures, so the catalysts can also be employed in the high temperature range.